Page 32 - Buried Pipe Design
P. 32
10 Chapter Two
supporting soil pressure. If the horizontal soil pressure and vertical
pressure are close to being equal, the load around the pipe approxi-
mates a hydrostatic load. The stresses in the pipe wall are then mainly
circumferential (hoop) compressive stresses, and for deep burial will
give rise to buckling.
Rigid pipe
Marston load theory. Anson Marston, who was dean of engineering at
Iowa State University, investigated the problem of determining loads
on buried conduits. In 1913, Marston published his original paper,
“The Theory of Loads on Pipes in Ditches and Tests of Cement and
Clay Drain Tile and Sewer Pipe.” 15 This work was the beginning of
methods for calculating earth loads on buried pipes. The formula is
now recognized the world over as the Marston load equation. More
recently, demands to protect and improve our environment and rising
construction costs have produced research that has substantially
increased our knowledge of soil structure interaction phenomenon.
However, much of this knowledge has yet to be applied to design prac-
tice. Many questions are as yet unresolved.
Anson Marston
